Heat a medium-sized cast-iron pan (about 2 inches deep) on high. When pan is hot, add a drop of sesame oil and add garlic and ginger so it starts sizzling. When an aroma releases, lower heat and add onion, then layer shitake mushrooms on top. Add a little water so the vegetables begins to steam. Let cook for about 2 minutes. Then layer over tomato, followed by the spinach and finally the 2 salmon filets. Drizzle remaining sesame oil and cover tightly with a lid. Keep heat on low. Cook for about 10-15 minutes or until salmon is medium-well.

To serve, use a large flat spatula and serve each filet over a bed of the steamed vegetables. Serve immediately.